I have the latest 1.4.21 patch and, just like 1.4.20, the game is stuttering constantly from everything I do, such as turning or even treading. Here's my hardware:

Nvidia GTX 285 1 GB EVGA
Intel 920 i7 2.6 ghz
6 GB of RAM
Windows 7 Ultimate

wait for the final release of the patch. Also try with a fresh SkyrimPrefs.ini.

Yes i would start by disabling all my mods ( if any), backup/delete your old ini file and produce a new one to test on, then re-verify the game cache, if the issues still persist then i would wait on the next patch i guess.